US9179822B2 - Endoscopic observation supporting system, method, device and program - Google Patents

Abstract

A virtual endoscopic image generating unit for generating, from a 3D medical image representing an interior of a body cavity of a subject formed by a 3D medical image forming unit and inputted thereto, a virtual endoscopic image, in which a position of a structure of interest identified by a position of interest identifying unit is a view point of the virtual endoscopic image, a real-time position of at least one of an endoscope and a surgical tool detected by an endoscope position detecting unit or a surgical tool position detecting unit is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image, is provided. A display control unit causes a WS display to display the generated virtual endoscopic image.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technology for supporting endoscopic observation during surgery or examination using an endoscope inserted in a body cavity of a subject, and in particular to a technology for supporting endoscopic observation using a virtual endoscopic image representing the interior of a body cavity of a subject.

2. Description of the Related Art

In recent years, surgery using an endoscope, such as laparoscopic surgery and thoracoscopic surgery, is drawing attention. The endoscopic surgery is advantageous in that it does not require laparotomy, thoracotomy, or the like, and only needs to make two or three holes of few centimeters in diameter for insertion of an endoscope and a surgical tool, thereby significantly reducing the burden imposed on the patient. However, conducting surgery with a very limited field of view of the endoscope is highly difficult, and doctors require a lot of skill to conduct the endoscopic surgery. If a blood vessel or an organ of the patient is damaged by mistake and breeds during the endoscopic surgery, it is impossible to continue the endoscopic surgery and the doctor has to conduct conventional surgery involving laparotomy, thoracotomy, or the like.

On the other hand, a virtual endoscopy technology for generating a virtual endoscopic image, which is similar to an endoscopic image, from a 3D volume image taken with a CT device, or the like, is known. This technology is widely used in North America as a method for finding a tumor, in particular, a colorectal tumor, only by CT imaging without conducting endoscopic examination.

Further, a technology for supporting endoscopic surgery using a virtual endoscopic image has been proposed.

For example, Japanese Unexamined Patent Publication No. 2002-263053 (hereinafter, Patent Document 1) has disclosed a device that detects a position of an endoscope with a sensor, generates a virtual endoscopic image having an angle of view wider than that of the endoscope with setting the detected position of the endoscope as a view point, and displays the virtual endoscopic image and a real endoscopic image taken with the endoscope superimposed one on the other.

Further, Japanese Unexamined Patent Publication No. 2005-021353 (hereinafter, Patent Document 2) has disclosed a device that detects a real-time position of an endoscope to generate a virtual endoscopic image having the same field of view as that of the endoscope, where location of blood vessels in the field of view is visualized. The device also detects a real-time position of a surgical tool used during endoscopic surgery to generate a composite image in which an image representing the surgical tool is combined at the position of the surgical tool in the virtual endoscopic image, and displays the composite image and a real endoscopic image.

The virtual endoscopic image according to the techniques disclosed in these documents, however, has the same view point as that of the real endoscopic image, i.e., is an image viewed from the same observation direction as that of the real endoscopic image. Therefore, depending on the positional relationship between a site of interest, such as a site of surgical interest, and the endoscope or the surgical tool, the site of interest may sometimes not be shown in the virtual endoscopic image or the real endoscopic image, and the doctor cannot recognize the approach of the endoscope or the surgical tool to the site of interest in such a case.

SUMMARY OF THE INVENTION

In view of the above-described circumstances, the present invention is directed to providing a system, a method, a device and a program for allowing the user to recognize the approach of an endoscope or a surgical tool to a site of interest, such as a site of surgical interest, more reliably during observation of a body cavity of a subject using the endoscope inserted in the body cavity.

An aspect of an endoscopic observation support system of the invention is an endoscopic observation support system comprising: 3D medical image forming means for forming a 3D medical image representing an interior of a body cavity of a subject; position of interest identifying means for identifying a position of a (first) structure of interest in the body cavity in the 3D medical image; position detecting means for detecting a real-time position of at least one of an endoscope and a surgical tool inserted in the body cavity; virtual endoscopic image generating means for generating, from the 3D medical image inputted thereto, a virtual endoscopic image representing the interior of the body cavity viewed from a view point, based on the identified position of the (first)) structure of interest and the detected position of at least one of the endoscope and the surgical tool in the 3D medical image, wherein the view point is the position of the (first) structure of interest, the position of at least one of the endoscope and the surgical tool is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image; and display means for displaying the virtual endoscopic image.

An aspect of an endoscopic observation support method of the invention is an endoscopic observation support method comprising the steps of: forming a 3D medical image representing an interior of a body cavity of a subject before or during observation of the interior of the body cavity with an endoscope inserted in the body cavity; identifying a position of a (first) structure of interest in the body cavity in the 3D medical image; detecting a real-time position of at least one of the endoscope and a surgical tool inserted in the body cavity; generating, from the 3D medical image inputted, a virtual endoscopic image representing the interior of the body cavity viewed from a view point, based on the identified position of the (first) structure of interest and the detected position of at least one of the endoscope and the surgical tool in the 3D medical image, wherein the view point is the position of the (first) structure of interest, the position of at least one of the endoscope and the surgical tool is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image; and displaying the virtual endoscopic image.

An aspect of an endoscopic observation support device of the invention is an endoscopic observation support device comprising: 3D medical image obtaining means for obtaining a 3D medical image representing an interior of a body cavity of a subject; position of interest identifying means for identifying a position of a (first) structure of interest in the body cavity in the 3D medical image; position obtaining means for obtaining a real-time position of at least one of an endoscope and a surgical tool inserted in the body cavity detected by position detecting means; virtual endoscopic image generating means for generating, from the 3D medical image inputted thereto, a virtual endoscopic image representing the interior of the body cavity viewed from a view point, based on the identified position of the (first) structure of interest and the detected position of at least one of the endoscope and the surgical tool in the 3D medical image, wherein the viewpoint is the position of the (first) structure of interest, the position of at least one of the endoscope and the surgical tool is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image; and display control means for causing display means to display the virtual endoscopic image.

An aspect of an endoscopic observation support program of the invention is an endoscopic observation support program for causing a computer to carry out the steps of: obtaining a 3D medical image representing an interior of a body cavity of a subject; identifying a position of a (first) structure of interest in the body cavity in the 3D medical image; obtaining a real-time position of at least one of an endoscope and a surgical tool inserted in the body cavity detected by position detecting means; generating, from the 3D medical image inputted, a virtual endoscopic image representing the interior of the body cavity viewed from a view point, based on the identified position of the (first) structure of interest and the detected position of at least one of the endoscope and the surgical tool in the 3D medical image, wherein the view point is the position of the (first) structure of interest, the position of at least one of the endoscope and the surgical tool is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image; and causing display means to display the real endoscopic image and the virtual endoscopic image.

Now, details of the invention are described.

In the invention, a real endoscopic image representing the interior of body cavity may be formed by real-time imaging with the endoscope, and the real endoscopic image which is formed almost at the same time when the position of at least one of the endoscope and the surgical tool used to generate the virtual endoscopic image is detected may further be displayed. In this manner, the real endoscopic image formed real-time by imaging with the endoscope and the virtual endoscopic image, which contains, in the field of view thereof, the real-time position of at least one of the endoscope and the surgical tool detected by the position detecting means almost at the same time when the real endoscopic image is formed, are displayed.

In a case where generation of the virtual endoscopic image is repeated in response to detection of the position of at least one of the endoscope and the surgical tool, real-time update of both the real endoscopic image and the virtual endoscopic image is achieved.

The real endoscopic image and the virtual endoscopic image may be displayed on a single display device or may be displayed separately on a plurality of display devices. The plurality of display devices may be located side by side at the physically same place so that both the images can be observed simultaneously, or may be located at places physically apart from each other so that the images are observed separately.

In the invention, in a case where the 3D medical image is obtained during observation using the endoscope, the 3D medical image may be obtained real-time. In this case, the position of at least one of the endoscope and the surgical tool may be detected by performing image recognition processing on the obtained 3D medical image.

Specific examples of the “(first) structure of interest” may include a site of surgical interest during endoscopic surgery and an anatomical structure that requires attention during endoscopic surgery, such as a blood vessel, an organ or a tumor. A specific method for identifying the position of the (first) structure of interest may be an automatic method using a known image recognition technique, a method involving manual operation by the user, or a method combining both the automatic and manual methods.

In the invention, a plurality of virtual endoscopic images may be generated by setting a plurality of positions of the (first) structure of interest as the view points.

The description “detecting . . . a position of at least one of an endoscope and a surgical tool” may refer to either of detecting the position of the endoscope when only the endoscope is inserted in the body cavity, or detecting the position of the endoscope, the position of the surgical tool, or both the positions of the endoscope and the surgical tool when the endoscope and the surgical tool are inserted in the body cavity.

The view point of the “virtual endoscopic image” is the position of the (first) structure of interest. However, the position of the view point is not strictly limited to a position on the surface of the (first) structure of interest or a position within the structure, and may be a position where an effect that is substantially equivalent to the effect of the invention is obtained, such as a position apart from the (first) structure of interest by few pixels.

The “virtual endoscopic image” contains the position of at least one of the endoscope and the surgical tool within the field of view thereof. This means that image information along a line of sight from the view point (the position of the (first) structure of interest) toward the position of at least one of the endoscope and the surgical tool is reflected in the virtual endoscopic image. If, for example, a structure, such as an organ, a blood vessel or a fold, is present between the (first) structure of interest and the endoscope or the surgical tool, the endoscope or the surgical tool may not necessarily be shown in the virtual endoscopic image.

Further, in the “virtual endoscopic image”, the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner. In a case where the 3D medical image is obtained before the endoscopic observation, the endoscope or the surgical tool has not yet been inserted in the body cavity of the subject when the 3D medical image is taken and obtained. Therefore, when the virtual endoscopic image is generated, a marker, or the like, representing the endoscope or the surgical tool may be combined at a position in the virtual endoscopic image corresponding to the position detected by the position detecting means. On the other hand, in a case where the 3D medical image is obtained real-time during the endoscopic observation and the endoscope or the surgical tool is shown in the image, the virtual endoscopic image may be generated such that the endoscope or the surgical tool is also shown in the virtual endoscopic image.

When the “virtual endoscopic image” is generated, a distance from the structure of interest to a surface of a structure in the body cavity may be used as a determinant of pixel values of the virtual endoscopic image. Alternatively, a color template, which is defined to provide the virtual endoscopic image showing sites in the body cavity in almost the same appearance as those shown in the real endoscopic image, may be used. It should be noted that the color template may include, for example, one that is defined such that each site in the body cavity has almost the same color of as that shown in the real endoscopic image, and each site in the body cavity may be shown semitransparent, as necessary, so that a structure behind an obstacle, which cannot be observed in the real endoscopic image, is visually recognizable in the virtual endoscopic image.

In the invention, a second structure of interest in the body cavity in the 3D medical image may be detected, and the virtual endoscopic image showing the detected second structure of interest in a visually recognizable manner may be generated. Specific examples of the “second structure of interest” may include those mentioned above with respect to the first structure of interest. Therefore, for example, the first structure may be a site of surgical interest during endoscopic surgery and the second structure of interest may be an anatomical structure that requires attention during the surgery, or vice versa.

In the invention, a warning may be shown when an approach of at least one of the endoscope and the surgical tool to the structure of interest satisfies a predetermined criterion. The warning may be visually shown in the virtual endoscopic image, or may be shown in a manner perceived by any other sense organ.

According to the invention, a 3D medical image representing an interior of a body cavity of a subject is obtained, a position of a structure of interest in the body cavity in the 3D medical image is identified, and a real-time position of at least one of an endoscope and a surgical tool inserted in the body cavity is detected. Then, from the 3D medical image inputted, a virtual endoscopic image is generated, wherein the view point of the virtual endoscopic image is the position of the structure of interest, the position of at least one of the endoscope and the surgical tool is contained in the field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image, and the virtual endoscopic image is displayed. The displayed virtual endoscopic image looks like an image taken with a camera that monitors the approach of the endoscope and the surgical tool to the structure of interest, such as a site of surgical interest or a site that requires attention. This virtual endoscopic image unique to the present invention compensates for the narrow field of view of the real endoscopic image, thereby allowing the user to more reliably recognize the approach of the endoscope or the surgical tool to the structure of interest and helping to prevent misoperation, etc., during surgery or examination.

Further, at this time, the field of view of the virtual endoscope of the continuously displayed virtual endoscopic image is changed real-time by feedback of the detected real-time position of the endoscope or the surgical tool. This allows the user to dynamically and more appropriately recognize the approach of the endoscope or the surgical tool to the structure of interest.

Still further, in the case where the real endoscopic image representing the interior of body cavity is formed by real-time imaging with the endoscope, and the real endoscopic image which is formed almost at the same time when the position of at least one of the endoscope and the surgical tool used to generate the virtual endoscopic image is detected is further displayed, the displayed real endoscopic image and virtual endoscopic image show the state of the interior of the body cavity almost at the same point of time, and the real endoscopic image and the virtual endoscopic image are continuously displayed in a temporally synchronized manner. Yet further, in the case where generation of the virtual endoscopic image is repeated in response to detection of the position of at least one of the endoscope and the surgical tool, real-time update of both the real endoscopic image and the virtual endoscopic image is achieved. That is, the field of view of the real endoscopic image changes along with movement or rotation of the endoscope, and the field of view of the virtual endoscopic image changes along with movement of the endoscope or the surgical tool. In this manner, the user can observe the interior of body cavity with complementarily using the real endoscopic image and the virtual endoscopic image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a hardware configuration diagram of an endoscopic observation support system according to embodiments of the present invention,

FIG. 2 is a functional block diagram of the endoscopic observation support system according to first to third embodiments of the invention,

FIG. 3 is a flow chart illustrating the flow of an endoscopic observation support process according to the first to third embodiments of the invention,

FIG. 4 is a diagram schematically illustrating one example of a positional relationship between a real endoscope, a surgical tool and a structure of interest, and angles of view of the real endoscope and a virtual endoscope,

FIG. 5 is a diagram schematically illustrating one example of a real endoscopic image that is displayed in the first embodiment of the invention,

FIG. 6 is a diagram schematically illustrating one example of a virtual endoscopic image that is displayed in the first embodiment of the invention,

FIG. 7A is a diagram schematically illustrating one example of a positional relationship between a structure of interest and a surgical tool,

FIG. 7B is a diagram schematically illustrating one example of the virtual endoscopic image that is displayed in the second embodiment of the invention,

FIG. 8A is a diagram schematically illustrating one example of a color template for changing a display color in the virtual endoscopic image depending on a distance from a view point to the surface of an anatomical structure in the abdominal cavity according to the third embodiment of the invention,

FIG. 8B is a diagram schematically illustrating one example of the virtual endoscopic image, in which the display color is changed depending on the distance from the view point, according to the third embodiment of the invention,

FIG. 9 is a functional block diagram of the endoscopic observation support system according to a fourth embodiment of the invention,

FIG. 10 is a flow chart illustrating the flow of the endoscopic observation support process according to the fourth embodiment of the invention,

FIG. 11 is a diagram schematically illustrating one example of a warning display according to the fourth embodiment of the invention,

FIG. 12 is a functional block diagram of the endoscopic observation support system according to a fifth embodiment of the invention,

FIG. 13 is a flow chart illustrating the flow of the endoscopic observation support process according to the fifth embodiment of the invention,

FIG. 14A is a diagram schematically illustrating one example of a positional relationship between a structure of interest and a structure that requires attention,

FIG. 14B is a diagram schematically illustrating one example of the virtual endoscopic image that is displayed in the fifth embodiment of the invention,

FIG. 15 is a functional block diagram of the endoscopic observation support system according to a sixth embodiment of the invention,

FIG. 16 is a flow chart illustrating the flow of the endoscopic observation support process according to the sixth embodiment of the invention,

FIG. 17A is a diagram schematically illustrating angles of view of the real endoscopic image and the virtual endoscopic image when the images are combined,

FIG. 17B is a diagram schematically illustrating one example of a composite image generated by combining the real endoscopic image and the virtual endoscopic image,

FIG. 18A is a diagram schematically illustrating another example of the real endoscopic image,

FIG. 18B is a diagram schematically illustrating one example of the virtual endoscopic image, which shows only blood vessels, and

FIG. 18C is a diagram schematically illustrating one example of a superimposed image of the real endoscopic image and the virtual endoscopic image.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an endoscopic observation support system according to embodiments of the present invention is described.

FIG. 1 is a hardware configuration diagram illustrating the outline of the endoscopic observation support system. As shown in the drawing, the system includes anendoscope1, adigital processor2, alight source device3, a realendoscopic image display4, amodality5, asurgical tool6, anendoscope marker7a, asurgical tool marker7b, aposition sensor8, animage processing workstation9, and an image processing workstation display (which will hereinafter be referred to as “WS display”)10.

In this embodiment, theendoscope1 is a hard endoscope for the abdominal cavity, and is inserted into the abdominal cavity of a subject. Light from thelight source device3 is guided by an optical fiber and emitted from the tip portion of theendoscope1, and an image of the interior of the abdominal cavity of the subject is taken by an imaging optical system of theendoscope1. Thedigital processor2 converts an image signal obtained by theendoscope1 into a digital image signal, and performs image quality correction by digital signal processing, such as white balance control and shading correction. Then, thedigital processor2 adds accompanying information prescribed by the DICOM (Digital Imaging and Communications in Medicine) standard to the digital image signal to output real endoscopic image data (I_RE). The outputted real endoscopic image data (I_RE) is sent to theimage processing workstation9 via a LAN according to a communication protocol conforming to the DICOM standard. Further, thedigital processor2 converts the real endoscopic image data (I_RE) into an analog signal and outputs the analog signal to the realendoscopic image display4, so that the real endoscopic image (I_RE) is displayed on the realendoscopic image display4. Theendoscope1 obtains the image signal at a predetermined frame rate, and therefore the real endoscopic image (I_RE) displayed on thereal endoscope display4 is a moving image showing the interior of the abdominal cavity. Theendoscope1 can also take a still image in response to an operation by the user.

Themodality5 is a device that images a site to be examined of the subject and generates image data (V) of a 3D medical image representing the site. In this embodiment, themodality5 is a CT device. The 3D medical image data (V) also has the accompanying information prescribed by the DICOM standard added thereto. The 3D medical image data (V) is also sent to theimage processing workstation9 via the LAN according to the communication protocol conforming to the DICOM standard.

Theendoscope marker7a, thesurgical tool marker7band theposition sensor8 form a known three-dimensional position measurement system. Theendoscope marker7aand thesurgical tool marker7bare provided in the vicinity of handles of theendoscope1 and thesurgical tool6, respectively, and three-dimensional positions of themarkers7a,7bare detected by theoptical position sensor8 at predetermined time intervals. Each of theendoscope marker7aand thesurgical tool marker7bis formed by a plurality of marker chips, so that theposition sensor8 can also detect the orientation of each of theendoscope1 and thesurgical tool6 based on a positional relationship among the marker chips, and three-dimensional positions (PS_E, PS_T) of the tip portions of theendoscope1 and thesurgical tool6 may be calculated by an offset calculation. Theposition sensor8 sends the calculated three-dimensional position data (PS_E, PS_T) of theendoscope1 and thesurgical tool6 to theimage processing workstation9 via a USB interface.

Theimage processing workstation9 is a computer having a known hardware configuration including a CPU, a main storage device, an auxiliary storage device, an input/output interface, a communication interface, a data bus, etc., to which an input device (such as a pointing device and a keyboard) and theWS display10 are connected. Theimage processing workstation9 is connected to thedigital processor2 and themodality5 via the LAN, and to theposition sensor8 via the USB connection. Theimage processing workstation9 has installed therein a known operating system, various application software programs, etc., and an application software program for executing an endoscopic observation support process of the invention. These software programs may be installed from a recording medium, such as a CD-ROM, or may be downloaded from a storage device of a server connected via a network, such as the Internet, before being installed.

FIG. 2 is a functional block diagram of the endoscopic observation support system according to a first embodiment of the invention. As shown in the drawing, the endoscopic observation support system according to the first embodiment of the invention includes theendoscope1, a real endoscopicimage forming unit2, the realendoscopic image display4, a 3D medicalimage forming unit5, thesurgical tool6, theWS display10, an endoscopeposition detecting unit11, a surgical toolposition detecting unit12, a real endoscopicimage obtaining unit21, an endoscopeposition obtaining unit22, a surgical toolposition obtaining unit23, a 3D medicalimage obtaining unit24, a position ofinterest identifying unit25, a virtual endoscopicimage generating unit26, and adisplay control unit27. It should be noted that the same reference numeral as that assigned to the hardware device shown inFIG. 1 is used to denote a corresponding functional block shown inFIG. 2 when there is substantially one to one correspondence between them. That is, the function of the real endoscopicimage forming unit2 is implemented by the digital processor shown inFIG. 1, and the function of the 3D medicalimage forming unit5 is implemented by the modality shown inFIG. 1. On the other hand, the function of the endoscopeposition detecting unit11 is implemented by theendoscope marker7aand theposition sensor8, and the function of the surgical toolposition detecting unit12 is implemented by thesurgical tool marker7band theposition sensor8. The dashed line frame represents theimage processing workstation9, and the functions of the individual processing units in the dashed line frame are implemented by executing predetermined programs on theimage processing workstation9. Further, a real endoscopic image I_RE, an endoscope position P_E, a surgical tool position P_T, a 3D medical image V, a position of interest P_Iand a virtual endoscopic image I_VEin the dashed line frame are data written in and read from predetermined memory areas of theimage processing workstation9 by the individual processing units in the dashed line frame.

Next, using the flow chart shown inFIG. 3, a schematic flow of operations by the user performed on the endoscopic observation support system and operations performed by the above-mentioned individual processing units according to the first embodiment of the invention is described.

Prior to observation of the interior of the abdominal cavity of a subject using theendoscope1, the 3D medicalimage forming unit5 images the interior of the abdominal cavity of the subject to form the 3D medical image V. On theimage processing workstation9, the 3D medicalimage obtaining unit24 obtains the 3D medical image V formed by the 3D medical image forming unit5 (#1), and then the position ofinterest identifying unit25 shows a user interface for receiving a user operation to specify a structure of interest (for example, a site of surgical interest) in the body cavity shown in the 3D medical image V obtained by the 3D medicalimage obtaining unit24, and identifies the position P_Iof the specified structure of interest in the 3D medical image V based on the obtained 3D medical image V (#2).

Then, as written on the right side of the flow chart shown inFIG. 3, during endoscopic surgery of the structure of interest, i.e., during observation of the interior of the abdominal cavity of the subject using theendoscope1, the real endoscopicimage forming unit2 repeatedly forms the real endoscopic image I_REtaken with theendoscope1 inserted in the body cavity at a predetermined frame rate, and the formed real endoscopic image I_REis displayed real-time as a live-view image on the realendoscopic image display4 until the observation is finished (#7: YES). Further, the endoscopeposition detecting unit11 and the surgical toolposition detecting unit12 repeatedly detect the real-time positions PS_E, PS_Tof theendoscope1 and thesurgical tool6 inserted in the body cavity at predetermined time intervals.

On theimage processing workstation9, the real endoscopicimage obtaining unit21 obtains the real endoscopic image I_REformed by the real endoscopic image forming unit2 (#3). Almost at the same time with this, the endoscopeposition obtaining unit22 obtains the endoscope position PS_Edetected by the endoscopeposition detecting unit11 and outputs the endoscope position P_E, which is obtained by converting the obtained endoscope position PS_Einto a position in the coordinate system of the 3D medical image V, and the surgical toolposition obtaining unit23 obtains the surgical tool position PS_Tdetected by the surgical toolposition detecting unit12 and outputs the surgical tool position P_T, which is obtained by converting the obtained surgical tool position PS_Tinto a position in the coordinate system of the 3D medical image V (#4).

The virtual endoscopicimage generating unit26 generates, from the 3D medical image V obtained by the 3D medicalimage obtaining unit24 and inputted thereto, the virtual endoscopic image I_VEbased on the position P_Iof the structure of interest identified by the position ofinterest identifying unit25, the endoscope position P_Eobtained by the endoscopeposition obtaining unit22, and the surgical tool position P_Iobtained by the surgical tool position obtaining unit23 (#5). The virtual endoscopic image I_VEis an image representing the interior of the abdominal cavity of the subject, where the position P_Iof the structure of interest is the view point and the surgical tool position P_Tis the center of the field of view. If the endoscope position P_Eis present in the field of view of the virtual endoscopic image I_VE, a shape image representing thesurgical tool6 and a shape image representing theendoscope1 are combined with the virtual endoscopic image I_VE.

Thedisplay control unit27 causes theWS display10 to display the real endoscopic image I_RE, obtained by the real endoscopicimage obtaining unit21 and the virtual endoscopic image I_VEgenerated by the virtual endoscopicimage generating unit26 side by side on a single screen (#6).

On theimage processing workstation9, operations to obtain a new real endoscopic image I_RE(#3), to obtain the endoscope position P_Eand the surgical tool position P_Tat that point of time (#4), to generate the virtual endoscopic image I_VE(#5) and to update the displayed real endoscopic image I_RE, and virtual endoscopic image I_VE(#6) are repeated, unless an operation to instruct to end the observation is made (#7: No). With this, the real endoscopic image I_RE, and the virtual endoscopic image I_VEare continuously displayed on theWS display10 in a temporally synchronized manner. When the operation to instruct to end the observation is made (#7: Yes), theimage processing workstation9 ends the repeated operations insteps #3 to #6 described above.

Next, details of the operations performed by the individual processing units in theimage processing workstation9 are described.

The real endoscopicimage obtaining unit21 is a communication interface that receives the real endoscopic image I_REvia communication with the real endoscopic image forming unit (digital processor)2 and stores the real endoscopic image I_REin a predetermined memory area of theimage processing workstation9. The real endoscopic image I_REis transferred from the real endoscopicimage forming unit2 based on a request from the real endoscopicimage obtaining unit21.FIG. 5 schematically illustrates one example of the real endoscopic image I_RE.

The endoscopeposition obtaining unit22 has a function of a communication interface to obtain the endoscope position PS_Evia communication with the endoscopeposition detecting unit11, and a function of converting the obtained endoscope position PS_Ein the 3D coordinate system of theposition sensor8 into the endoscope position P_Erepresented by coordinate values in the 3D coordinate system of the 3D medical image V and storing the endoscope position P_Ein a predetermined memory area of theimage processing workstation9. With respect to the former communication interface function, the endoscope position PS_Eis obtained from the endoscopeposition detecting unit11 based on a request from the endoscopeposition obtaining unit22. With respect to the latter coordinate transformation function, an amount of rotation of coordinate axes is calculated in advance based on a correspondence relationship between the orientation of each coordinate axis in the 3D coordinate system of the position sensor and the orientation of each coordinate axis in the 3D coordinate system of the 3D medical image V, and coordinate values of a position on the subject corresponding to the origin of the 3D medical image V in the 3D coordinate system of theposition sensor8 are measured in advance to calculate an amount of translation between the coordinate axes based on the coordinate values of the origin. Then, the conversion of the endoscope position PS_Erepresented by the 3D coordinate system of theposition sensor8 into the endoscope position P_Erepresented by the coordinate values in the 3D coordinate system of the 3D medical image V can be achieved using a matrix that applies rotation by the calculated amount of rotation and translation by the calculated amount of translation.

Similarly to the endoscopeposition obtaining unit22, the surgical toolposition obtaining unit23 has a function of a communication interface to obtain the surgical tool position PS_Tvia communication with the surgical toolposition detecting unit12, and a function of converting the obtained surgical tool position PS_Tin the 3D coordinate system of theposition sensor8 into the surgical tool position P_Trepresented by the coordinate values in the 3D coordinate system of the 3D medical image V and storing the surgical tool position P_Tin a predetermined memory area of theimage processing workstation9.

The 3D medicalimage obtaining unit24 has a function of a communication interface to receive the 3D medical image V from the 3D medicalimage forming unit5 and store the 3D medical image V in a predetermined memory area of theimage processing workstation9.

The position ofinterest identifying unit25 shows, on a cross-sectional image representing a predetermined cross-section generated from the 3D medical image V using the known MPR method, a user interface for receiving an operation to specify the structure of interest via the pointing device or keyboard of theimage processing workstation9. For example, when the pointing device is clicked on the structure of interest shown in the cross-sectional image, the position ofinterest identifying unit25 identifies the position P_Iof the structure of interest, which has been specified by the click, in the 3D medical image V, and stores the position P_Iin a predetermined memory area of theimage processing workstation9. As the structure of interest, a site of surgical interest or a site that requires attention during surgery may be specified, as desired by the user.

The virtual endoscopicimage generating unit26 generates the virtual endoscopic image I_VEfrom the 3D medical image V inputted thereto based on the position P_Iof the structure of interest, the endoscope position P_Eand the surgical tool position P_T.FIG. 4 schematically illustrates one example of a positional relationship among theendoscope1, thesurgical tool6 and the structure of interest P_I, and angles of view of theendoscope1 and the virtual endoscope. As shown in the drawing, the virtual endoscopicimage generating unit26 uses the position P_Iof the structure of interest as the view point and the surgical tool position P_Tas the center of the field of view to set a plurality of lines of sight radiating from the view point P_Iwithin the range of an angle of view A_V, and generates a preliminary virtual endoscopic image by projecting pixel values along each line of sight by volume rendering using the known perspective projection. The angle of view A_Vof the preliminary virtual endoscopic image is set to be wider than an angle of view A_Rof the real endoscopic image I_REthrough startup parameters of the program. For the volume rendering, a color template is used, which defines color and transparency in advance such that an image having almost the same appearance as that of the sites in the abdominal cavity shown in the real endoscopic image I_REis obtained. Further, the virtual endoscopicimage generating unit26 generates a surgical tool shape image M_Tshowing a state where thesurgical tool6 is present at the surgical tool position P_T, and an endoscope shape image M_Eshowing a state where theendoscope1 is present at the endoscope position P_Eif the endoscope position P_Eis present in the field of view of the virtual endoscopic image. Specifically, the surgical tool shape image M_Tand the endoscope shape image M_Eare generated based on images representing the shapes of theendoscope1 and thesurgical tool6 stored in a database, as well as the surgical tool position P_Tand the endoscope position P_E, as taught in the above-mentionedPatent Document 2. Then, the virtual endoscopicimage generating unit26 generates the virtual endoscopic image I_VEby combining the preliminary virtual endoscopic image with the surgical tool shape image M_Tand the endoscope shape image M_Eby a known technique, such as alpha blending.FIG. 6 schematically illustrates one example of the thus generated virtual endoscopic image I_VE, wherein the shape image M_Trepresenting thesurgical tool6 is superimposed at the surgical tool position P_Tat the near center of the field of view, and the shape image M_Erepresenting theendoscope1 is superimposed at the endoscope position P_Ein the field of view, and the image as a whole virtually represents a state where the interior of the abdominal cavity is viewed with an endoscope from the position of the structure of interest P_Ishown inFIG. 4 during endoscopic surgery.

Thedisplay control unit27 generates a display screen where the real endoscopic image I_REand the virtual endoscopic image I_VEare displayed side by side on a single screen and outputs the generated screen to theWS display10. In this manner, the display screen where the real endoscopic image I_REschematically shown inFIG. 5 as an example and the virtual endoscopic image I_VEschematically shown inFIG. 6 as an example are displayed side by side is displayed on theWS display10.

As described above, in the first embodiment of the invention, prior to observation of the interior of the abdominal cavity using theendoscope1, the 3D medicalimage obtaining unit24 obtains the 3D medical image V formed by the 3D medicalimage forming unit5, and the position ofinterest identifying unit25 identifies the position P_Iof the structure of interest in the abdominal cavity in the 3D medical image V. During the observation, the real endoscopicimage obtaining unit21 obtains the real endoscopic image I_REformed by the real endoscopicimage forming unit2, and at the same time, the endoscopeposition obtaining unit22 obtains the position P_Eof theendoscope1 in the 3D medical image V detected by the endoscopeposition detecting unit11 and the surgical toolposition obtaining unit23 obtains the position P_Tof thesurgical tool6 in the 3D medical image V detected by the surgical toolposition detecting unit12. Then, the virtual endoscopicimage generating unit26 generates, from the 3D medical image V, the virtual endoscopic image I_VE, in which the position P_Iof the structure of interest is the view point and the surgical tool position P_Tis the center of the field of view, and theendoscope1 and thesurgical tool6 are combined at the endoscope position P_Eand the surgical tool position P_T, respectively. Then, thedisplay control unit27 causes theWS display10 to display the real endoscopic image I_REand the virtual endoscopic image I_VE. The thus displayed virtual endoscopic image I_VElooks like an image taken with a camera that monitors the approach of theendoscope1 and thesurgical tool6 to the position P_Iof the structure of interest. By using the virtual endoscopic image I_VEto compensate for the narrow field of view of the real endoscopic image I_RE, the approach of theendoscope1 and thesurgical tool6 to the structure of interest can be recognized more reliably, thereby helping to prevent misoperation, or the like, during surgery or examination.

Further, at this time, the field of view of the virtual endoscope of the continuously displayed virtual endoscopic image I_VEis changed real-time by feedback of the real-time positions of theendoscope1 and thesurgical tool6 detected by the endoscopeposition detecting unit11 and the surgical toolposition detecting unit12. This allows the user to dynamically and more appropriately recognize the approach of theendoscope1 and thesurgical tool6 to the structure of interest.

Further, the real endoscopicimage forming unit2 forms the real endoscopic image I_RErepresenting the interior of body cavity taken real-time with theendoscope1, and the real endoscopic image I_REwhich is formed almost at the same time when the position of theendoscope1 or thesurgical tool6 used to generate the virtual endoscopic image I_VEis detected is further displayed. The real endoscopic image I_REand the virtual endoscopic image I_VEshow the state of the interior of the body cavity almost at the same point of time, and the real endoscopic image I_REand the virtual endoscopic image I_VEare continuously displayed in a temporally synchronized manner. Further, at this time, the field of view of the real endoscopic image I_REchanges along with movement or rotation of theendoscope1, and the field of view of the virtual endoscopic image I_VEchanges along with movement of thesurgical tool6. In this manner, in the first embodiment of the invention, the user can observe the interior of body cavity with complementarily using the real endoscopic image I_REand the virtual endoscopic image I_VE.

Still further, the virtual endoscopicimage generating unit26 generates the virtual endoscopic image I_VEusing the color template, which defines color and transparency in advance such that an image having almost the same appearance as that of the sites in the abdominal cavity shown in the real endoscopic image I_REis obtained. Therefore, the user can observe both the real endoscopic image I_REand the virtual endoscopic image I_VEdisplayed side by side on theWS display10 by thedisplay control unit27 without a feel of inconsistency.

A second embodiment of the invention is a modification of a volume rendering process carried out by the virtual endoscopicimage generating unit26. The hardware configuration, the functional blocks and the overall flow of the process of the endoscopic observation support system of the second embodiment are the same as those in the first embodiment.

FIG. 7A schematically illustrates one example of a positional relationship between the structure of interest and thesurgical tool6. As shown in the drawing, in a case where there is an anatomical structure that obstructs the view between the position P_Iof the structure of interest, which is used as the view point of the virtual endoscopic image I_VE, and the surgical tool position P_T, if the color template is defined to provide the anatomical structure with high opacity, thesurgical tool6 behind the anatomical structure is not shown in the virtual endoscopic image I_VE. Therefore, in the second embodiment of the invention, the virtual endoscopicimage generating unit26 generates the virtual endoscopic image I_VEusing a color template that defines opacity such that the sites in the body cavity are shown semitransparent. In the thus generated virtual endoscopic image I_VE, as schematically shown inFIG. 7B, the anatomical structure present between the position P_Iof the structure of interest and the surgical tool position P_Tis shown semitransparent, and the surgical tool shape image M_Tis shown in a visually recognizable manner at a position corresponding to the surgical tool position P_Tbehind the anatomical structure. Such an image where an anatomical structure in the abdominal cavity is shown semitransparent cannot be formed by the real endoscopicimage forming unit2, and therefore practical value of using the virtual endoscopic image I_VEshowing such a semitransparent anatomical structure complementarily to the real endoscopic image I_REis very high.

A third embodiment of the invention is also a modification of the volume rendering process carried out by the virtual endoscopicimage generating unit26. The hardware configuration, the functional blocks and the overall flow of the process of the endoscopic observation support system of the third embodiment are the same as those in the first embodiment.

FIG. 8A schematically illustrates one example of the color template used in the third embodiment of the invention. As shown in the drawing, this color template is defined such that the color of the virtual endoscopic image I_VEis changed depending on a distance from the view point P_Ion the structure of interest to the surface of a structure in the abdominal cavity. For example, the virtual endoscopicimage generating unit26 detects, a position where a change of pixel value along each line of sight of the perspective projection is larger than a predetermined threshold or a position where the pixel value is equal to or larger than a predetermined threshold as the surface of a structure in the abdominal cavity, and calculates the distance from the view point P_Ito the surface of the structure in the abdominal cavity. Then, the virtual endoscopicimage generating unit26 uses the color template to determine the pixel value of the detected surface of the structure shown in the virtual endoscopic image I_VE. The thus generated virtual endoscopic image I_VEhas a thinner color at the surface of a structure nearer to the position P_Iof the structure of interest, and a denser color at the surface of a structure farther from the position P_Iof the structure of interest, as schematically shown inFIG. 8B as an example. In this manner, depth perception of the virtual endoscopic image I_VE, which is hard to be perceived, can be compensated for, thereby facilitating the user to recognize the approach of theendoscope1 and thesurgical tool6. It should be noted that the color and density of the shape image M_Eof theendoscope1 and the shape image M_Tof the surgical tool displayed in the virtual endoscopic image I_VEmay also be changed depending on the distance from the position P_Iof the structure of interest in a manner similar to that described above.

As shown in the functional block diagram ofFIG. 9, a fourth embodiment of the invention includes awarning determination unit28 in addition to the components of the first embodiment. The hardware configuration of the endoscopic observation support system of the fourth embodiment is the same as that in the first embodiment.

Thewarning determination unit28 is a processing unit implemented on theimage processing workstation9. Thewarning determination unit28 calculates a distance between the endoscope position P_Eand the position P_Iof the structure of interest and a distance between the surgical tool position P_Tand the position P_Iof the structure of interest. If either of the calculated distance is smaller than a predetermined threshold, i.e., if theendoscope1 or thesurgical tool6 approaches too close to the structure of interest, thewarning determination unit28 outputs a warning message WM.

FIG. 10 is a flow chart illustrating the flow of the endoscopic observation support process according to the fourth embodiment of the invention. As shown in the drawing, after the real endoscopic image I_REand the virtual endoscopic image I_VEare displayed instep #6 of the first embodiment, thewarning determination unit28 compares each of the above-described distances with the threshold (#11). If either of the above-described distances is smaller than the threshold (#11: Yes), thewarning determination unit28 outputs the warning message WM, and thedisplay control unit27 superimposes an arrow mark with a comment “CAUTION—APPROACHING” in the vicinity of the displayedendoscope1 or the surgical tool6 (theendoscope1 is shown in the drawing) that is too close to the structure of interest, and shows the shape image representing theendoscope1 or surgical tool in a denser display color, as shown inFIG. 11 as an example. This facilitates the user to recognize the abnormal approach of theendoscope1 or thesurgical tool6 to the structure of interest, thereby helping to prevent misoperation of theendoscope1 and thesurgical tool6. Such a warning display is particularly effective when a blood vessel, or the like, which will cause massive bleeding if it is damaged during surgery, is specified as the structure of interest at the position ofinterest identifying unit25.

Besides being superimposed on the displayed virtual endoscopic image I_VE, as described above, the warning message may be outputted in the form of a warning sound or voice, or may be outputted both as the superimposed warning message and the warning sound. Further, a risk determination table that defines a risk depending on the distance in a stepwise manner may be prepared in advance, and thewarning determination unit28 may reference the risk determination table based on the calculated distance to determine the risk, and the determined value of the risk may be outputted as the warning message WM and thedisplay control unit27 may display an icon, or the like, corresponding to the risk on theWS display10.

As shown in the functional block diagram ofFIG. 12, a fifth embodiment of the invention includes an attention-requiredstructure detecting unit29 in addition to the components of the first embodiment. The hardware configuration of the endoscopic observation support system is the same as that of the first embodiment.

The attention-requiredstructure detecting unit29 is a processing unit implemented on theimage processing workstation9. The attention-requiredstructure detecting unit29 detects a region of attention-required structure RA from the 3D medical image V inputted thereto using a known image recognition technique.FIG. 14A schematically illustrates one example of a positional relationship between the structure of interest and the attention-required structure. In this example, the attention-requiredstructure detecting unit29 detects an attention-required blood vessel region RA that is located behind the abdominal wall by performing known blood vessel extraction processing.

FIG. 13 is a flow chart illustrating the flow of the endoscopic observation support process according to the fifth embodiment of the invention. As shown in the drawing, after the position of interest P_Iis identified instep #2 of the first embodiment, the attention-requiredstructure detecting unit29 detects the region of attention-required structure RA (#13). Instep #5, the virtual endoscopicimage generating unit26 generates the virtual endoscopic image I_VEusing a color template that is defined to show the region of attention-required structure RA in a visually recognizable manner.FIG. 14B schematically illustrates one example of the generated virtual endoscopic image I_VE. The virtual endoscopic image I_VEshown in the drawing is generated using a color template that defines color and opacity such that pixels representing the abdominal wall are shown semitransparent to increase the visual recognizability of pixels representing the blood vessel. This increases the visual recognizability of the attention-required structure, thereby helping to prevent misoperation of theendoscope1 and thesurgical tool6, similarly to the fourth embodiment.

It should be noted that the attention-requiredstructure detecting unit29 may detect the region of attention-required structure RA via manual operation by the user. Further, a marker, such as an arrow, and an annotation, such as a text comment, may be superimposed on the region of attention-required structure RA.

In a sixth embodiment of the invention, the 3D medical image V is formed and obtained real-time during the observation using the endoscope. In this case, theendoscope marker7a, thesurgical tool marker7band theposition sensor8 in the hardware configuration of the first embodiment (seeFIG. 1) are not necessary.

FIG. 15 is a functional block diagram of the endoscopic observation support system according to the sixth embodiment of the invention. As shown in the drawing, the endoscopic observation support system of the sixth embodiment includes an endoscope/surgical toolposition recognition unit30 in place of the endoscopeposition detecting unit11, the surgical toolposition detecting unit12, the endoscopeposition obtaining unit22 and the surgical toolposition obtaining unit23 of the first embodiment. That is, the endoscope/surgical toolposition recognition unit30 corresponds to the position detecting means of the invention.

The endoscope/surgical toolposition recognition unit30 is a processing unit implemented on theimage processing workstation9. The endoscope/surgical toolposition recognition unit30 extracts an area showing theendoscope1 or thesurgical tool6 from the 3D medical image V inputted thereto using known pattern recognition processing to recognize the endoscope position P_Eand the surgical tool position P_T.

FIG. 16 is a flow chart illustrating the flow of the endoscopic observation support process according to the sixth embodiment of the invention. As shown in the drawing, after the real endoscopic image I_REis obtained instep #3 of the first embodiment, the 3D medicalimage obtaining unit24 obtains the 3D medical image V (#14), and the endoscope/surgical toolposition recognition unit30 recognizes the endoscope position P_Eand the surgical tool position P_Tbased on the 3D medical image V obtained by the 3D medical image obtaining unit24 (#15). Instep #5, the virtual endoscopicimage generating unit26 generates the virtual endoscopic image I_VEusing a color template that is defined such that the area showing theendoscope1 or thesurgical tool6 extracted by the endoscope/surgical toolposition recognition unit30 is displayed in a predetermined color. Therefore, it is not necessary to generate the shape images of theendoscope1 and thesurgical tool6 as in the first embodiment. By forming and obtaining the 3D medical image V real-time during the observation using the endoscope in this manner, the obtained 3D medical image V shows the state of the interior of the abdominal cavity almost at the same point of time as that shown in the real endoscopic image I_RE. Therefore, the generated virtual endoscopic image I_VEmore accurately shows the real-time state of the interior of the abdominal cavity than a case where the 3D medical image V obtained before the observation using the endoscope is used. It should be noted that, when the 3D medical image V is taken insteps #1 and #14 in this embodiment, it is necessary to pay attention to the posture of the subject during imaging so that the position of the subject corresponding to the origin of the coordinate axes and the orientation of the coordinate axes are not changed.

In the sixth embodiment of the invention, it is preferable to use an ultrasound diagnostic device as themodality5, in view of reducing radiation exposure of the subject.

The above-described embodiments are merely examples and should not be construed as limiting the technical scope of the invention.

Further, variations and modifications made to the system configuration, the hardware configuration, the process flow, the module configuration, the user interface and the specific contents of the process of the above-described embodiments without departing from the scope and spirit of the invention are also within the technical scope of the invention.

For example, with respect to the system configuration, although themodality5 is directly connected to theimage processing workstation9 in the hardware configuration ofFIG. 1 of the above-described embodiments, an image storage server may be connected to the LAN and the 3D medical image V formed by themodality5 may once be stored in a database of the image storage server, so that the 3D medical image V is transferred from the image storage server to theimage processing workstation9 in response to a request from theimage processing workstation9.

Theendoscope1 may not be a hard endoscope, and a soft endoscope or a capsular endoscope may be used.

As themodality5, besides the above-mentioned CT device and the ultrasound diagnostic device, a MRI device, etc., may be used.

TheWS display10 may be a display that supports known stereoscopic display to display the virtual endoscopic image I_VEwhich is a stereoscopic image. For example, in a case where theWS display10 is a display device that achieves stereoscopic display using two parallax images for right and left eyes, the virtual endoscopicimage generating unit26 may generate virtual endoscope parallax images for right and left eyes by setting positions of right and left eyes, which are shifted from the position P_Iof the structure of interest by an amount of parallax between the right and left eyes, and performing perspective projection with using the thus set right and left eye positions as the view points. Then, thedisplay control unit27 may exert control such that display pixels of theWS display10 for the left eye to display the virtual endoscope parallax image for the left eye and display pixels of theWS display10 for the right eye to display the virtual endoscope parallax image for the right eye.

The endoscopeposition detecting unit11 and the surgical toolposition detecting unit12 may use a magnetic system, or may use a gyro or a rotary encoder, as taught inPatent Document 2.

The body site to be observed may be a site of the subject which is suitable for observation using an endoscope, such as the interior of the thoracic cavity, other than the interior of the abdominal cavity.

In the above-described embodiments, theimage processing workstation9 receives the image based on a request from the real endoscopicimage obtaining unit21 with taking the communication load into account, assuming that a cycle at which the real endoscopicimage forming unit2 forms the real endoscopic image I_REis shorter than a cycle at which the virtual endoscopicimage generating unit26 generates the virtual endoscopic image I_VE. However, the real endoscopicimage obtaining unit21 may receive all the real endoscopic images IE sequentially formed by the real endoscopicimage forming unit2. In this case, thedisplay control unit27 may update the displayed real endoscopic image I_REon theWS display10 each time the real endoscopic image I_REis received, asynchronously with the timing of generation of the virtual endoscopic image I_VEby the virtual endoscopicimage generating unit26.

The endoscopeposition obtaining unit22 may receive all the endoscope positions PS_Edetected at predetermined time intervals by the endoscopeposition detecting unit11, and may convert only the endoscope position PS_Ewhich is received at the time when the operation instep #4 ofFIG. 3 is invoked into the endoscope position P_Eby the coordinate transformation function to output it. The same applies to the surgical toolposition obtaining unit23.

The coordinate transformation carried out by the endoscopeposition obtaining unit22 and the surgical toolposition obtaining unit23 in the above-described embodiments may be carried out by the virtual endoscopicimage generating unit26.

The position ofinterest identifying unit25 may automatically identify the position of interest using a known image recognition technique (such as a technique for extracting blood vessels or an organ or a technique for detecting an abnormal shadow).

The virtual endoscopicimage generating unit26 may set the endoscope position P_Eat the center of the field of view so that theendoscope1 is always within the field of view, in place of setting the surgical tool position P_Tat the center of the field of view so that thesurgical tool6 is always within the field of view. Further alternatively, an internally dividing point of the segment P_E-P_T, such as a midpoint between the endoscope position P_Eand the surgical tool position P_T, may be set at the center of the field of view, and the angle of view may be set such that both theendoscope1 and thesurgical tool6 are within the field of view. Still alternatively, the angle of view and a magnification factor may be adjusted depending on distances between the position P_Tof the structure of interest, the endoscope position P_Eand the surgical tool position P_T. For example, if the distances between these positions are small, the angle of view may be set narrower and the magnification factor may be set larger than those when the distances between these positions are large, so that the area in the field of view is magnified to facilitate the observation.

In place of combining the shape image representing theendoscope1 or thesurgical tool6 with the virtual endoscopic image I_VE, a marker, such as an arrow, may be displayed at the endoscope position P_Eor the surgical tool position P_T.

The virtual endoscopicimage generating unit26 may generate the virtual endoscopic images I_VEviewed from a plurality of view points by setting a plurality of positions of interest, such as a site of surgical interest, an attention-required blood vessel and an attention-required organ, as the view points.

Theimage processing workstation9 may generate and display an image other than the above-described real endoscopic image I_REand virtual endoscopic image I_VE. For example, a virtual endoscopic image with a wider angle of view A_Vthan the angle of view A_Eof theendoscope1, as schematically shown inFIG. 17A as an example, may further be generated with setting the endoscope position P_Eas the view point and using a magnification factor that renders the size of an object of interest in the image almost the same size as that in the real endoscopic image I_RE, and a new image, as schematically shown inFIG. 17B as an example, where the real endoscopic image is superimposed on the thus generated virtual endoscopic image with aligning the center of the field of view, i.e., the endoscope position P_E, may be generated and displayed.

Alternatively, a composite image of the real endoscopic image and the virtual endoscopic image may be generated. For example, a virtual endoscopic image showing only a visualized blood vessel structure, as schematically shown inFIG. 18B as an example, may be combined with a real endoscopic image, as schematically shown inFIG. 18A as an example, to generate a real endoscopic image with the emphasized blood vessel structure, as schematically shown inFIG. 18C as an example.

Claims (14)

The invention claimed is:

1. An endoscopic observation support system comprising:

a 3D medical image forming unit configured to form a 3D medical image representing an interior of a body cavity of a subject;

a position of interest identifying unit configured to identify a position of a structure of interest in the body cavity in the 3D medical image, the structure of interest being a site of surgical interest or an anatomical structure that requires attention during endoscopic surgery;

a position detecting unit configured to detect a real-time position of at least one of an endoscope and a surgical tool inserted in the body cavity;

a virtual endoscopic image generating unit configured to generate, from the 3D medical image inputted thereto, a virtual endoscopic image representing the interior of the body cavity viewed from a view point, based on the identified position of the structure of interest and the detected position of at least one of the endoscope and the surgical tool in the 3D medical image, wherein the view point is the position of the structure of interest, the position of at least one of the endoscope and the surgical tool is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image; and

a display control unit configured to cause a display unit to display the virtual endoscopic image.

2. The endoscopic observation support system as claimed inclaim 1, further comprising

a real endoscopic image forming unit configured to form a real endoscopic image representing the interior of body cavity by real-time imaging with the endoscope,

wherein the display control unit further causes the real endoscopic image which is formed almost at the same time when the position of at least one of the endoscope and the surgical tool used to generate the virtual endoscopic image is detected to be displayed.

3. The endoscopic observation support system as claimed inclaim 1, wherein the virtual endoscopic image generating unit determines pixel values of the virtual endoscopic image depending on a distance from the structure of interest to a surface of a structure in the body cavity.

4. The endoscopic observation support system as claimed inclaim 1, further comprising a warning unit configured to show a warning when an approach of at least one of the endoscope and the surgical tool to the structure of interest satisfies a predetermined criterion.

5. The endoscopic observation support system as claimed inclaim 1, wherein the virtual endoscopic image generating unit determines pixel values of the virtual endoscopic image using a color template, wherein the color template is defined to provide the virtual endoscopic image showing sites in the body cavity in almost the same appearance as those shown in a real endoscopic image obtained by imaging with the endoscope.

6. The endoscopic observation support system as claimed inclaim 1, further comprising

a second structure of interest detecting unit configured to detect a second structure of interest in the body cavity in the 3D medical image,

wherein the virtual endoscopic image generating unit generates the virtual endoscopic image in which the second structure of interest is shown in a visually recognizable manner.

7. The endoscopic observation support system as claimed inclaim 6, wherein the structure of interest is a site of surgical interest during endoscopic surgery using the endoscope and the second structure of interest is an anatomical structure that requires attention during the endoscopic surgery.

8. The endoscopic observation support system as claimed inclaim 1, wherein the position of the endoscope is contained in a field of view of the virtual endoscopic image, and the position of the endoscope is shown in an identifiable manner in the virtual endoscopic image.

9. An endoscopic observation support method comprising the steps of:

forming a 3D medical image representing an interior of a body cavity of a subject before or during observation of the interior of the body cavity with an endoscope inserted in the body cavity;

identifying a position of a structure of interest in the body cavity in the 3D medical image, the structure of interest being a site of surgical interest or an anatomical structure that requires attention during endoscopic surgery;

detecting a real-time position of at least one of the endoscope and a surgical tool inserted in the body cavity;

generating, from the 3D medical image inputted, a virtual endoscopic image representing the interior of the body cavity viewed from a view point, based on the identified position of the structure of interest and the detected position of at least one of the endoscope and the surgical tool in the 3D medical image, wherein the view point is the position of the structure of interest, the position of at least one of the endoscope and the surgical tool is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image; and

displaying the virtual endoscopic image.

10. The endoscopic observation support method as claimed inclaim 9, wherein the position of the endoscope is contained in a field of view of the virtual endoscopic image, and the position of the endoscope is shown in an identifiable manner in the virtual endoscopic image.

11. An endoscopic observation support device comprising:

a 3D medical image obtaining unit configured to obtain a 3D medical image representing an interior of a body cavity of a subject;

a position of interest identifying unit configured to identify a position of a structure of interest in the body cavity in the 3D medical image, the structure of interest being a site of surgical interest or an anatomical structure that requires attention during endoscopic surgery;

a position obtaining unit configured to obtain a real-time position of at least one of an endoscope and a surgical tool inserted in the body cavity detected by a position detecting unit;

a virtual endoscopic image generating unit configured to generate, from the 3D medical image inputted thereto, a virtual endoscopic image representing the interior of the body cavity viewed from a view point, based on the identified position of the structure of interest and the detected position of at least one of the endoscope and the surgical tool in the 3D medical image, wherein the view point is the position of the structure of interest, the position of at least one of the endoscope and the surgical tool is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image; and

a display control unit configured to cause a display unit to display the virtual endoscopic image.

12. The endoscopic observation support device as claimed inclaim 11, wherein the position of the endoscope is contained in a field of view of the virtual endoscopic image, and the position of the endoscope is shown in an identifiable manner in the virtual endoscopic image.

13. A non-transitory computer readable medium containing an endoscopic observation support program for causing a computer to carry out the steps of:

obtaining a 3D medical image representing an interior of a body cavity of a subject;

identifying a position of a structure of interest in the body cavity in the 3D medical image, the structure of interest being a site of surgical interest or an anatomical structure that requires attention during endoscopic surgery;

obtaining a real-time position of at least one of an endoscope and a surgical tool inserted in the body cavity detected by a position detecting unit;

generating, from the 3D medical image inputted, a virtual endoscopic image representing the interior of the body cavity viewed from a view point, based on the identified position of the structure of interest and the detected position of at least one of the endoscope and the surgical tool in the 3D medical image, wherein the view point is the position of the structure of interest, the position of at least one of the endoscope and the surgical tool is contained in a field of view of the virtual endoscopic image, and the position of at least one of the endoscope and the surgical tool is shown in an identifiable manner in the virtual endoscopic image; and

causing a display unit to display the virtual endoscopic image.

14. The non-transitory computer readable medium as claimed inclaim 13, wherein the position of the endoscope is contained in a field of view of the virtual endoscopic image, and the position of the endoscope is shown in an identifiable manner in the virtual endoscopic image.

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